Occurrence and effect of PACAP in the human fetal adrenal gland.

In the study reported in this paper, we characterized PACAP in the human fetal adrenal gland and we investigated the effect of PACAP on steroid secretion from cultured fetal adrenal cells. The adrenal gland from 20-week-old fetuses contained substantial concentrations of PACAP-immunoreactive material (88.6 ng/g wet tissue). HPLC analysis of adrenal extracts revealed the presence of both PACAP27 and PACAP38, the latter being the predominant form. Incubation of cultured fetal adrenal cells with PACAP38 (10(-7) M) significantly increased cortisol and DHEAS secretion. Administration of the beta-adrenoreceptor agonist isoproterenol mimicked the stimulatory effect of PACAP on both steroid secretion whereas preincubation of fetal cells with the beta-adrenoreceptor antagonist propranolol suppressed the steroidogenic effect of PACAP. These data, together with the observation that PACAP receptors are exclusively located on chromaffin cells, suggest that, in the fetal human adrenal gland, the effect of PACAP on steroid secretion is mediated via the local release of catecholamines.